Process for refining crude oleoresin



Patented F eb. 19, 1946 PROCESS FOR REFINING'CRUDE OLEQItESlN Kay-V.Lawrence, Newbrleans, La., assignor to the United States of America asrepresented by the Secretary of Agriculture No Drawing. ApplicationDecember 5, 1944,

Serial No: 566,778

(Cl. 260-109) e (Granted under the act of March 3, 1883,'a

7 Claims.

amended April 30, 1928; 3700. G. 757) This application is made under theact of March 3, 1883, as amended by the act of April 30, 1928, and, theinventionherein described and claimed, if patented, may be manufacturedand used by or for the Government of the United States .of America forgovernmental purposes without the payment to me of any royalty thereon Ve This is a continuation in'part of my copending application for patentSerial No. 412,004, filed September 23, 1941.

This. invention relates to the refining of crude pine. oleoresin, andthe general object is to improve the grade of rosin'which may be madefrom pine oleoresin.

Crude oleoresin is some extent by dissolved iron compounds. 7 Upon thedistillation of the oleoresin, the iron compounds remain-in the rosin.The presence of relatively small amounts of iron greatly increase thecolor of the rosin produced, resulting in a much lower grade product.The presence of iron in rosin is also known to increase the rate atwhich the rosin combines with oxygen on exposure to the air.

the color of rosin and oleoresin which are contaminated by iron has beenknown andpracticed by the trade for some time. However, when oleoresinthat is badly contaminated with increased by the addition of sodiumchloride or 4 great extent on usually contaminated to as The .useofoxalic acid for the improvement of iron is treated with oxalic acid, therosin pro- .duced is frequently quite cloudy and in some cases opaque.The material causing the cloudinessis very finely divided and difficultto remove. I have foundthatthis matrial'is insoluble in water and inaqueous oxalic acid solutions, but

that a clear rosin of improved grade can be produced from ironcontaminated oleoresin by treating-it with an aqueous solutioncontaining both ioxalic acid and an inorganic acid. I have alsofound'that similar results maybe obtained by treating iron contaminatedoleoresin with oxalic "acid and following this by a treatment with anaqueous solution of an inorganic acid due to the factthat the waterinsoluble material formed by the oxalic acidis, as I have found, solublein aqueous solutions of inorganic acids,

* The coloring matter present in oleoresin is usually of two diiferenttypes, 1. e., that caused by iron contamination and that caused byoxidation products. Since the treatment of oleoresin with oxalic acidand inorganic acid mixtures will have very little effect on the coloringmatter derived from oxidation products, the color of the final productafter-such a treatment will depend to a the amount of oxidation productsin the original oleoresin. Thus,'a badly oxidized oleoresin may show animprovement of only: one or two grades while another oleoresin in whichmost of the color is caused by iron contamination may show animprovement of seven or eigh grades.

My invention may be carried out in a number of ways. The crude oleoresinmay be treated with an aqueous acid solution whose density has beensodium sulfate to such an extent that the aqueous layer will separatefrom the oleoresin, However, I prefer to dissolve the crude oleoresin ina water immiscible organic solvent and separate the water and foreignmaterial from the oleoresin solution. The solvent used-should beinactive towards the oleoresin constituents and'the acid-treatingsolutions. I have found turpentine, benzene, and gasoline to be suitablesolvents. However, I prefer to use gu'm turpentine since this does notinvolve thev problem f-separating the turpentine present in theoleoresin from the solvent used for dilution. The amount of solvent usedmay vary widely. I have found asolution which yields 40 to rosin ondistillation to be convenient for carrying out this process.

The concentration of oxalic acid used is not critical.Satisfactory'results have been obtained using aqueous solutions varyingin concentration from 1% to a saturated solution. The crystallinedihydrate of oxalic acid may also be added directly to the oleoresin.The use of such crystals in the amount of 0.1 to 3% by weight of theoleoresin to be treated is satisfactory. A molar solution (approximately9%) was found to be a convenient concentration for the oxalic acidsolution. If the concentration of the inorganic acid used is toogreat,considerable isomerization of the constituents of the oleoresin may takeplace. Concentrations of the inorganic acids used, varying from 1 normalto 2 normal, were found to be satisfactory.

The optimum temperature for carrying out a,- this process will varysomewhat depending on the nature and amount of solvent used forvdissolving the oleoresin. An oleoresin solution prepared. by dissolving100 parts, by weight, of oleoresin in 40 parts, by weight, of gumturpentine gave satisfactory results when treated according to thisprocess at temperatures between 60 and C. A solution prepared usingparts, by Weight, of oleoresin in- 100 parts of petroleum ether (13. P.3,0- 60" ;C.) gave satisfactory results temperature (25-30 0.).

The following examples illustrate, but do not limit, my invention:

EXAMPLES 1 r '7 at temperatures varying from 65 to 80 C. After aqueoussolutions had been thoroughly mixed with the oleoresin solution, theaqueous solution was allowed to separate by gravity from the-oleoresinsolution, and the oleoresin solution washed with distilled water. Thegrades and appearance of the rosin samples .obtained by the steamdistillation of these samples are given in Table I.

I Table I aranc No. Washmg solution 22 5 g g e 100 ml. distilled water DClear. 100 ml. 9% aqueous oxalic acid N Very cloudy. 100 ml. 5%aqueous-sulfuric acid... M Clear. 90 ml. 5% aqueous sulfuric acid and NDo.

ml. 9%. aqueous oxalic acid. 5. 90 ml. 5% aqueous oxalic acidand 10 NDo.

m1.,5% aqueous sulfuric acid. 6. 90 ml. 9% aqueous oxalic acid and 10 NDo.

ml. 5% aqueous hydrochloric acid. 7. 90 ml. 9% aqueous oxalic acid and10 N Do.

ml. 5% phosphoric acid.

EXAMPLES 8 TO 12 A stock solution of oleoresin was prepared bydissolving 1860 grams of low grade oleoresin in 500 grams of petroleumether (B. P. 35-60 C.) and filtering. Samples of this solution, 150 ml.each, were washed by shaking in a separatory funnel with 50 ml. ofmixtures of aqueous 'solutions of sulfuric and oxalic acid. After theacid washing was completed, the aqueous layer was separated from theoleoresin solution, and the oleoresin solution was washed with water toremove traces of theacid washing solution. The

EXAMPLE 13 A solution of oleoresin in turpentine was filtered to removetrash and extraneous matter. A sample of this solution on distillationshowed a composition of 48% turpentine, by weight, and 52% rosin with acolor grade of D. A 350 gram sample of this solution was washed bythoroughly shaking with 100 ml. of a 10% solution of aqueous oxalic acidatapproximately 60 C. The solutions were allowed to separate and theaqueous layer drawn off. The oleoresinsolution was hen washed with 100ml. of a 5% aqueous sulfuric acid solution at approximately 60 C. The

when treated according to this process at room aqueous layer was drawnof! and the oleoresin washed with water to remove the acid washingsolutions. The washed oleoresin was distilled in the usual manner andyielded a clear rosin of color grade N.

' EXAMPLE 14 In this case, Example 3 was repeated with the exceptionthat after the oleoresin solution was washed with 10% oxalic acidsolution, it was washed with 100 of 3% aqueous hydrochloricacidsolution. The oleoresin yielded a clear rosin of'color grade N.

EXAMPLE 15 A 250 gram sample of crude gum, a sample of which ondistillation yielded 20.8% of turpentine, 2.2% water and 77.0% rosin ofgrade D, was treated with 2.5 grams solid oxalic acid (the dihydrate) atapproximately 75 C. for minutes with occasional shaking. The oleoresinwas dissolved in 100 grams of freshly distilled gum turpentine, and theresulting solution was washed by thorough shaking with two 100 m1.portions of aqueous sulfuric acid solution containing 10% sulfuric acidby weight. After separation of the aqueous acid solution, the oleoresinsolution was washed with three 100 ml. portions of distilled water. Theoleoresin was separated from the wash water and steam distilled. A clearrosin 80 of grade N was obtained.

Having thus described my invention, I claim: 1. The method of refiningcrude oleoresin containing iron and other acid soluble contaminatingmaterials, comprising mixing and washing 85 the oleoresin with anaqueous solution of oxalic acid containing from 0.5 to 5%, by weight, ofan inorganic acid, and then separating the aqueous acid solution, whichwill contain the contaminatingmaterials, from the oleoresin.

2. The method of refining crude oleoresin containing iron and other acidsoluble contaminating materials, comprising mixing and washing theoleoresin with an aqueoussolution of oxalic acid containing from 0.5 to5%, by weight, of sulfuric acid, and then separating the aqueous acidsolution, which will contain the contaminating materials, from the.oleoresin.

3. The method of refining crude oleoresin containing iron and other acidsoluble contaminating .materials, comprising mixing and washing theoleoresin with an aqueous solution of oxalic acid containing from 0.5 to5%, by weight, of hydrochloric acid, and then separating the aqueousacid solution, which will contain the contaminating materials, from theoleoresin.

4. The method of refining crude oleoresin containing iron and other acidsoluble contaminating materials, comprising mixing and washing theoleoresin with an aqueous solution of oxalic acid containing from 0.5 to5%, by weight, of phosphoric acid, and then separating the aqueous acidsolution, which will contain the contaminating materials, from theoleoresin.

5. The method of refining crude oleoresin containing iron and other acidsoluble contaminating materials, comprising mixing and washing theoleoresin with an aqueous oxalic acid solution, then separating thesolution from the oleoresin, then washing and mixing the oleoresin withan aqueous inorganic acid solution containing 0.5 to 5%, by weight, orthe inorganic acid, and then separating the aqueous acid so- .lutionfrom the oleoresin.

6. Themethod of refining crude oleoresin-containing iron and other acidsoluble impurities.

7. The method or refining crude oleoresin containing iron and otheracid-soluble contaminating materials comprising mixing and washing theoleoresin with an aqueous solution of oxalic acid and an aqueoussolution of 0.5 to 5.0% by weight of an inorganic acid, and thenseparating the aqueous acid solution from the oleoresin.

RAY V. LAWRENCE.

